"During the course of his statement, he indicated that while he was attacking Mr. Boone, he was checking for guards," assistant county prosecutor Michelle Gasparian said during Tuesday's hearing. Authorities have said Gaines initially tried to strangle Boone with a ripped bed sheet as he slept, then eventually slammed Boone's head against the concrete floor and stomped on his head until he believed Boone was dead.

Gaines faces $1 million bail for the murder charge stemming from Boone's death, and another $1 million for an attempted murder charge stemming from the other jail attack. The latter incident, which had occurred two days earlier inside a gym area, left another inmate hospitalized with serious injuries.

Gaines initially was being held at the jail in connection with a February 2012 robbery and carjacking. His bail for those counts was set at $100,000.